Myth busters

May 5, 2014
44
Oday Daysailer II Eugene, OR
Should be no problem if the wind doesn't shift.
(Sorry. That belongs in Famous Last Words rather than Myths.)
 

Sailm8

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Feb 21, 2008
1,751
Hunter 29.5 Punta Gorda
Honey, "Look how many steaks fit in the freezer" "The freezer sure keeps them hard"
 
Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
With respect to number 5: Yogi Berra once is said to have said, "In theory there is no difference between theory and practice. In practice there is." Theory states that the "hull speed" - maximum speed of a displacement boat - can be closely approximated in knots by 1.39 times the square root of the water line in feet. The displacement hull sits in the trough between the trailing edge of the bow wave and the leading edge of the stern wave created as the hull moves through the water. The bow and stern wave fronts move together at a speed proportional to their separation distance. So in theory there is a limit to how fast a displacement hull moves -- namely the maximum speed of these two wave fronts. In practice however, once a sail boat reaches hull speed additional energy usually produces excessive heal, wind is dumped out of the sails, and the boat stays in the trough. In practice, even a displacement hull can be forced to ride up onto the trailing edge of the bow wave forcing the boat to go faster than the theoretical hull speed without getting up on a plane.
First, unless your boat floats by not breaking the surface tension of the water, it is a DISPLACEMENT BOAT. All boats are!

Now, if your boat as a high enough downwind SA/D ratio, say 45:1; there is a good chance it will lift off the water and plane, IF it has a planing hull form. Flat wide aft sections are a good clue. This form is good for speed but compromised other aspects for cruisers, so it is not used unless that boat actually has a chance to plane.

I sail on a bunch of boats that plane all the time. But when not moving, or moving slow, they all are displacement boats.
 
Mar 26, 2011
3,961
Corsair F-24 MK I Deale, MD
(after a botched docking attempt)

"What happens in Deale, stays in Deale."

As though that weren't bad enough. I practiced docking.
 
Mar 26, 2011
3,961
Corsair F-24 MK I Deale, MD
"This is my last boat."

(I really hoped it was true this time. I've already cheated, buying 2 kayaks.)
 
Feb 21, 2010
362
Beneteau 31 016 St-Lawrence river
The two happiest days in a boat-owners life are the day he buys and the day he sells!
 

Scott

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Sep 24, 1997
242
Hunter 31_83-87 Middle River, Md
With respect to number 5: Theory states that the "hull speed" - maximum speed of a displacement boat - can be closely approximated in knots by 1.39 times the square root of the water line in feet.
I thought it was 1.34 times. My boat should go faster! :D
 
May 5, 2014
44
Oday Daysailer II Eugene, OR
US Sailing says the hull speed coefficient is 1.34. But as pointed out earlier, that's a myth for planing hulls. The not-very-helpful-for-sailboats-planing-hull calculators generally rely on weight and horsepower. Perhaps another myth is that you can easily find anything you need related to sailing on the Web.